The users installed version of Excel

With every new release of Excel, the issue of compatibility rears its head. As I write this, Excel 2007 has just been released - yet many large corporations are still using Excel 2000 and some use even earlier versions.

Unfortunately, there is no guarantee that an application developed for, say, Excel 2000 will work perfectly with later versions of Excel. If you need your application to work with a variety of Excel versions, the best approach is to work with the lowest version - and then test it thoroughly with all other versions.

Things get even more complicated when you consider Excel's sub-versions. Microsoft distributes service releases (SRs) to correct problems. For example, users might have the original Excel 2000, Excel 2000 with SR-1, or Excel 2000 with SR-2. And it gets even more complicated with Excel 2003. Excel 2007 has a quite a few known problems, and it's likely that at least some of them will be corrected in a future service release.